36. Valid Sudoku

https://leetcode.com/problems/valid-sudoku
Python

from collections import defaultdict


class Solution:
    def isValidSudoku(self, board: List[List[str]]) -> bool:
        col_table = defaultdict(set)
        row_table = defaultdict(set)
        cell_table = defaultdict(set)

        for row, row_values in enumerate(board):
            for col, value in enumerate(row_values):
                if value == '.':
                    continue

                cell_key = "{}{}".format(
                    row//3,
                    col//3
                )

                if value in col_table[col] or \
                   value in row_table[row] or \
                   value in cell_table[cell_key]:
                    return False

                col_table[col].add(value)
                row_table[row].add(value)
                cell_table[cell_key].add(value)

        return True
Python​

Python
